Thomas a



(No Model.)

T. A. EDISON. INGANDESGENT ELEUTRIG LAMP.

No. 454,558. Patented June 23,1891.

WITNESSES INVIINTOR ATTORN UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF MENLO PARK, NEIV JERSEY, ASSIGNOR TO THE EDISONELECTRIC LIGHT COMPANY, OF NEW YORK, N. Y.

INCANDESCENT ELECTRIC LAMP.

SPECIFICATION forming part of Letters Patent No. 454,558, dated June 23,1891.

Application filed August 7, 1882- Serial No. 68,606. (No model.)

To aZZ whom it may concern:

Be it known that I, THOMAS A. EDISON, of Menlo Park, in the county ofMiddlesex and State of New Jersey, have invented new and usefulImprovements in Incandescing Electric Lamps and I do hereby declare thatthe following is a full and exact description of the same, referencebeing had to the accompanying drawings, and to the letters of referencemarked thereon.

The object of my invention is to produce an incandescent electric lampin which one double-limbed carbon is used made integral throughout itslength, such carbon being so arranged and connected that both limbs maybe used together in series in the ordinary manner, or both maybe used inmultiple arc, or either limb may be used separately without the other.

In carrying my invention into effect the limbs of the carbon (which isthe ordinary horseshoe carbon commonly employed by me) are supported inthe usual manner by electroplating to leading-in wires sealed in theglass of the inclosing globe. Between these leading-in wires is sealed athird, which extends up between the limbs of the carbon, and is attachedat the center of the arch or loop by electroplating thereto. hen allthese wires are properly connected to the system, the current passesthrough the central wire and is divided between the two limbs of thecarbon, the latter thus being in multiple arc. If the central wire isdisconnected and the two limbs attached to opposite wires of the system,the two are of course in series,or it one limb of the carbon isdisconnected the other may be used separately. This may be betterunderstood by reference to the accompanying drawing, in which the figurerepresents the carbon and connections, the globe of the lamp beingomitted.

A is the interior supporting tube or stem of an incandescent lamp. 1 2are the leadingin wires sealed therein and supporting the limbs C C ofthe carbon, to which they are secured by electroplating. A thirdleadingin wire 3 is also sealed in the glass stem A, and is attachedabove at the center of the arch by electroplating the wire to the carbonat b.

Suitable arrangements of contacts and cir cuit-controllers are made inthe base of the lamp or elsewhere, so that the proper connections forthe various uses of the lamp may be made, as described.

What I claim is- In an incandescent electric lamp, the combination of aninclosing globe, a continuous integral loop'shaped carbon filamenttherein, conducting-wires attached to the ends of said filament andextending outside the globe for electrical connection with an externalcircuit, and a third conducting-wire connected with the middle point ofthe filamentary loop and also extending outside the globe for electricalconnection, substantially as set forth.

This specification signed and witnessed this 5th day of December, 1881.

T. A. EDISON.

Witnesses:

H. W. SEELY, WM. II. MEADowoRoFT.

